This is not going to be a full review, the 550EXR arrived Wednesday so I have not had any real Quality time with it as yet.
However my initial impression is WOW!!
I have tried many high end amps in my system and this just blew me away. Fast detailed, refined. You get the idea. This made a jaw dropping difference in the sonic presentation.
Jaw dropping is not something I expect from a power amp. They all sound the same as you know.
Frank this is a real giant killer, way to go!!
I do have a couple of negatives though. The Binding posts could be ( much ) better and ( although I don't see how ) better placed. Spade connections are very difficult.
Overall a minor point, but some times it is the little things that frustrate the most.
Regards,
Bill
PS this is a reprint of the same in the Critics Circle.